1. Field of the Art
This invention relates to a liquid feed device for use on endoscopes, and more particularly to a liquid feed device which is especially suitable for use on endoscopes as an auxiliary water feed mechanism for spurting a jet of water or other liquids from a liquid injection port opened at a distal end of an endoscopic insertion tube.
2. Prior Art
Generally, a plural number of water feed/discharge means are provided on endoscopes. A first example is a body fluid suction or aspiration means. As a body fluid suction means, normally a suction passage is connected to a biopsy channel within an insertion tube of an endoscope, and a vacuum pump or a suction device is connected to the proximal end of the suction passage. At the time of aspiration, a suction valve which is provided on a manipulating head assembly of the endoscope is operated by an operator.
Further, generally a wash fluid or cleaning fluid feed means is provided on endoscopes for the purpose of sprinkling a cleaning fluid on an endoscopic observation window which is provided on a rigid tip end section at the distal end of the insertion tube. A cleaning liquid (normally wash water) and compressed air are generally employed as cleaning fluids. When an observation window is smudged with contaminants, firstly a cleaning liquid is spurted on the observation window to wash away deposited contaminants and then compressed air is blasted to remove droplets of the cleaning liquid. Therefore, an air feed passage is provided on an endoscope along with a liquid feed passage. Air/water feed valves which are provided on the manipulating head assembly of the endoscope are operated at the time of feeding a cleaning liquid or compressed air through the liquid feed passage or the air feed passage. At a point in the vicinity of the distal end portion of the insertion tube, the liquid feed passage and the air feed passage are joined together into a joined fluid passage leading to a nozzle which is provided on a tip end section of the insertion tube to spurt a cleaning fluid toward the observation window of the endoscope. Firstly, a cleaning liquid is supplied to the nozzle through the liquid feed passage and the joined fluid passage by putting the air/water feed valve in a liquid feed position. Then, the air/liquid feed valve is switched to an air feed position for spurting out compressed air from the nozzle through the air feed passage and the joined fluid passage. Therefore, when an observation window at the distal end of an insertion tube is smudged with contaminants, it can be washed clean without extracting the insertion tube from a body cavity.
Further, still another liquid feed device is incorporated in some endoscopes for spurting water into a body cavity under high pressure for the purpose of washing intracavitary walls or for sprinkling a coloring pigment or other liquid or solutions. This liquid feed device has a liquid injection hole or port opened at a distal end of the insertion tube to spurt a jet of a necessary liquid into a body cavity. In this case, a liquid is spurted in the direction of a view filed of the observation window of the endoscope, different from the above-mentioned cleaning liquid which is spurted toward and on the endoscopic observation window itself.
As described above, the liquid feed device is provided with a liquid injection port at the distal end of the insertion tube. As pressurized liquid feed means to be employed for sending a liquid under pressure, a syringe or a liquid pumping means is detachably connected to a liquid feed port which is provided on the casing of the manipulating head assembly of the endoscope. The liquid feed port is connected with the liquid injection port by a flexible tube internally providing a liquid feed passage. Normally, the pressure within a body cavity is higher than the atmospheric pressure. Therefore, there is possibilities of a liquid in the liquid feed passage or fluids in a body cavity flowing in a reverse direction, that is, in an outward direction and flowing out of the liquid inlet. In order to prevent this, the liquid feed port has to be retained in a closed state when no liquid is fed to the liquid feed passage. More particularly, for this purpose, a check valve is provided on the side of the liquid feeder, thereby normally blocking communication between the liquid feed passage and the atmosphere. When a pressurized liquid feed means is connected to feed a liquid under high pressure, the check valve is opened to permit supply of the liquid toward the liquid injection port through the liquid feed passage.
An endoscope has to be washed and disinfected each time after use. In washing and disinfecting a used endoscope, it is important to reprocess not only the liquid injection port which is opened at the distal end of the insertion tube, but also internal portions of the liquid feed passage which is in communication with the liquid injection port. A cleaning liquid and a disinfectant liquid are fed under pressure toward the liquid supply passage and the liquid injection port by connecting a syringe or a pressurized liquid feed means which is filled with a cleaning liquid or a disinfectant. In some cases, the liquid injection port and the liquid feed passage are scrubbed by inserting a brush into the liquid feed passage through the liquid injection port.
However, the check valve which is provided on the side of a liquid feed device becomes an obstacle in a washing operation, more specifically, an obstacle to the supply of cleaning and disinfectant liquids in a washing operation or to the insertion of a cleaning brush in a scrubbing operation. Therefore, as known from Japanese Patent No. 2980232, for example, there have been introduced endoscopic liquid feed devices employing a detachable check valve on the side of a liquid feed port.
The above-mentioned Japanese patent shows arrangements, in which either a valve member of a check valve of the liquid feeder is detachably fitted in a liquid feed passage, or a passage forming member with a check valve is threaded into a female screw portion in a mouth piece of a liquid feeder.
In a case where a valve member is detachably fitted in a liquid feed passage as in the above-mentioned Japanese patent, there is a problem of damages to the valve member, caused by a hooking jig which is necessarily used at the time of forcibly mounting or dismantling the valve member into or out of the liquid feed passage. On the other hand, in a case where a check valve is built in a passage forming member to be threaded into a mouth piece of a liquid feeder, the existence of the female screw on the inner periphery of the mouth piece makes it difficult to connect a syringe of a cleaning liquid or a disinfectant for washing the liquid feed passage up to the liquid injection port at the distal end of the insertion tube.